The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results s...The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results show that the chemical composition and activity of the catalysts are greatly changed with the variation of calcination temperature. The catalyst Au/Fe2O3 calcined at 200℃, highly dispersed particles with the partially oxidized gold species on the support with the mean diameter of 3nm～5nm, displayes the best activity and selectivity of CO selective oxidation. However, the catalytic activity of Au/Fe2O3 decreases drastically with increasing calcination temperature due to the aggregation of metallic gold and bigger particle sizes. It is found that the catalytic behavior is related to the gold particle size but the nature of the support. On the basis of characterization data, in addition to the particle size of metallic gold, the oxidation states of gold are proven to be important for CO selective oxidation in H2-rich gas.展开更多
The core-shell Fe2O3@Au particle with spindle morphology were synthesized by three steps.The mean size of the core-shell paricles was about 500 nm by 85 nm.The final single separated spindle particles were attached on...The core-shell Fe2O3@Au particle with spindle morphology were synthesized by three steps.The mean size of the core-shell paricles was about 500 nm by 85 nm.The final single separated spindle particles were attached onto Si substrates.The thiophenol(TP) was served as probe molecule to investigate the pola-rized dependent surface-enhanced Raman scattering(SERS) from single particle.Dramatic variations in SERS intensity was observed when the single core-shell particle was oriented at different angles relative to the polarization of excitation laser.The maximum SERS intensity was detected for TP absorbed on the anisotropic particle which was in the polarization direction parallel to the long axis of the particle,while the minimum intensity was detected at the direction of the incident field that is perpendicular to the long axis of the particle.Our preliminary results provided useful way for obtaining deeper insight to the SERS mechanism.展开更多
文摘The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results show that the chemical composition and activity of the catalysts are greatly changed with the variation of calcination temperature. The catalyst Au/Fe2O3 calcined at 200℃, highly dispersed particles with the partially oxidized gold species on the support with the mean diameter of 3nm～5nm, displayes the best activity and selectivity of CO selective oxidation. However, the catalytic activity of Au/Fe2O3 decreases drastically with increasing calcination temperature due to the aggregation of metallic gold and bigger particle sizes. It is found that the catalytic behavior is related to the gold particle size but the nature of the support. On the basis of characterization data, in addition to the particle size of metallic gold, the oxidation states of gold are proven to be important for CO selective oxidation in H2-rich gas.
文摘The core-shell Fe2O3@Au particle with spindle morphology were synthesized by three steps.The mean size of the core-shell paricles was about 500 nm by 85 nm.The final single separated spindle particles were attached onto Si substrates.The thiophenol(TP) was served as probe molecule to investigate the pola-rized dependent surface-enhanced Raman scattering(SERS) from single particle.Dramatic variations in SERS intensity was observed when the single core-shell particle was oriented at different angles relative to the polarization of excitation laser.The maximum SERS intensity was detected for TP absorbed on the anisotropic particle which was in the polarization direction parallel to the long axis of the particle,while the minimum intensity was detected at the direction of the incident field that is perpendicular to the long axis of the particle.Our preliminary results provided useful way for obtaining deeper insight to the SERS mechanism.
